Mobile Setup – December 2016


18Dec16 – Got the mobile going again and had a good test session with the Aloha Net on 40m.

  • Rig: FT-857D
  • LDG-YT-100 auto tuner + remote tuning button
  • Separation Kit YSK-857 – plastic front panel holder, microphone and front panel cables allowing  ±10′  of separation.
  • 857 and yt-100 mounted piggyback rear passenger floor
  • 857 front panel mounted on wood bracket inserted into dashboard receptacle
  • short RJ11 6 wire,front panel connector attached to mounting strap (don’t lose it!)
  • Antenna – MFJ 1640T – 7′ overall length- center loaded  with steel stinger – 3/8″ standard thread.
  • magmount – 3 magnet – RG58 feedline
  • Mount position – roof –
    • front:back- center of rear seat window
    • left:right – center
  • Battery  10AH  LiFePO4
  • Final rig setup adjustments after testing with kh6io after net:
    • PROC menu 74  : 50   down from  80
    • SSB Gain  menu 81:   80   down from 100
    • mic to mouth orientation: close 2″, talk across the mic (thumb facing mouth)
      • produced better power
    • mic switch #2  (no change)

The FT-857D and YT-100 are mounted in a piggy back configuration with the YT100 on top on the back seat floorboard on the transmission well running down the cars interior centerline.  The front panel of the 857 is mounted on the front dashboard with a home-made bracket. To activate the auto-tuner, I made a remote switch for the YT100 from a 3.5mm stereo plug and cable and SPST push button switch.   The front panel, microphone, and remote autotuner cable run forward to the cockpit.

Battery power: I have fused, 12 ga stranded wire cables with Anderson power pole connectors running from the car battery to the radio.  In addition, a 10AH LiFepo4 battery can be plugged in for “mobile at rest” operation.  This battery has a much flatter discharge curve than the car starter battery.  That second battery helps to to stay out of the trouble that comes from being unable to start the car engine due to a drained battery.

Initial transmission- SWR was high and the rig was folding back with diagnostic assist from  IB and HI.  A full tune with LDG fixed it.
Bert kh6hi gave me a report of +5 (down 10dB from home dipole – roughly 2 S units)
KK6APA in Kalapana report was 57 to 59.
ah6IO and kh6IMB easy  copy  to Volcano – S9 report.
IO reported pronounced 857D audio sound. After the net a short QSO helped a bit and produced final rig adjustments.

Antenna and Tuning
The antennas are mounted on a 3 magnet mount.  While I haven’t done extensive tests, SWR on my  2004 Buick LeSabre is lowest in the center of the roof.  The magnets provide capacitive coupling to the the steel roof which together with the unibody / frame comprise the antenna counterpoise.  
I get SWRs for the MFJ hamtenna antennas- typically about  1.5:1  or 2:1  at best.  40m SWR to 4:1 or worse on the far side of the band.   1/2″ of adjustment of the stinger whip are required for lowest SWR across the 40m band.


SWR effects: The LDG tuner easily handles SWR  issues difference with the antennas if you’re in the ballpark.  The 857 is pretty aggressive on clipping power with high SWR and re-tuning is very effective.  A remote tuning switch makes it possible to activate the tuner from the cockpit.

Above: Remote tuning cable schematic.

Location notes – Kaonohi Street
Best location for radio on Kaonohi St:  near the golf course ( around elev 116m/364ft)  east side facing mauka around the BWS water tank on the Ewa side of the road.   This location happens to be one farthest away from homes and has a golf-course on one side.  Noise level: S2.

Worst: parking lot in my house has highest audible hash noise level (not necessarily measures on the S meter).  S6/S7 meter noise most of Kaonohi St.  The S meter level doesn’t tell the whole story with noise- the hash you can hear is not uniform and receiving is best when you can’t hear the noise.  Kaonohi Neighborhood park is OK.  Much of the residential streets have fairly high noise.  The top of the hill is bad for noise.  Side streets have high hash noise level.

857 Birdies?
During the net, there were discreet musical notes as you tune up/down 40 meters and the one at 7.188 was strong enough to interfere.  Strong signals chased them away.   They may have subsided over time.

Temperature in the Car.
The FT-857D specifications show operations up to 140º F.  Dashboard temperatures at 1200 noon in full sun were 134º F under the sun-shade!   Air temps in the cooler parts of the car are less than 90º F but on hot days will likely reach 100º F everywhere.

Well, no DX yet, but local range out to 250 miles or so to the Big Island makes it serviceable for emergency HF communications.

JT65 / fldigi and DX

Coming up


~ by marksun on December 21, 2016.

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